A guide to designing future ground-based cosmic microwave background experiments

In this follow-up work to the high energy physics Community Summer Study 2013 (aka SNOWMASS), we explore the scientific capabilities of a future Stage IV cosmic microwave background polarization experiment under various assumptions on detector count, resolution, and sky coverage. We use the Fisher matrix technique to calculate the expected uncertainties of cosmological parameters in νΛCDM that are especially relevant to the physics of fundamental interactions, including neutrino masses, effective number of relativistic species, dark energy equation of state, dark matter annihilation, and inflationary parameters. To further chart the landscape of future cosmology probes, we include forecasted results from the baryon acoustic oscillation signal as measured by Dark Energy Spectroscopic Instrument to constrain parameters that would benefit from low redshift information. We find the following best 1σ constraints: σ(M _ν) = 15 meV, σ(N _eff) = 0.0156, dark energy figure of merit = 303, σ(p _ann) = 0.00588 × 3 × 10^–26 cm³ s^–1 GeV^–1, σ(Ω _K) = 0.00074, σ(n_s ) = 0.00110, σ(α _s) = 0.00145, and σ(r) = 0.00009. We also detail the dependencies of the parameter constraints on detector count, resolution, and sky coverage.